What Is A LSAW Pipe?
LSAW Pipe (Longitudinal Submerged Arc-Welding Pipe), is taking the steel plate as raw material, mold it by the molding machine, then do double-sided submerged arc welding. Through this process the LSAW steel pipe will get excellent ductility, weld toughness, uniformity, plasticity and great sealing.
Diameters range and performances of LSAW pipe
Pipe O.D: Ф406.4～Ф1422.4mm（16-56in）
Pipe Length: Max.12.2m(40ft)
Wall Thickness: When the steel grade is X70, the wall thickness ranges from 6.4 to 26.4mm(0.252–1.04in);
When the steel grade is lower, the wall thickness will be increased accordingly
Product Standard: ISO3183-3; API Spec 5L, GB9711
Capacity: The annual output is 0.2million tons
Legnth:8-12.15m Material: API 5L Gr.B-X80, Standard: API spec. 5L; GB9711.1-97
Range of LSAW pipes applied in construction
Range of roller pipes: Outer diameter: Ф1200-3800mm | Wall thickness: 12-120mm | Unit length (max) 3.2m.
Note: The specification in the table is available to Q345. Remarks: non-standard dimensions pipes can be produced to customer specifications.
Range of Roller Pipes
|1||Material yield limited||
|3||Maximum pre-bending thickness||mm||110||90||100|
|4||Maximum width of steel plate||mm||3200||3200||3200|
|5||Minimum diameter of fully loaded rolling steel plate||mm||2500||1600||1600|
(Uing and Oing forming) UOE Pipes
SSAW pipe Manufacturing Process
SSAW Pipe (Spiral Submerged Arc-Welding Pipe), also called HSAW pipe, welding line shape like a helix. It is using the same welding technology of Submerged Arc-Welding with LSAW pipe. Differently SSAW pipe is spiral welded where the LSAW is longitudinally welded. Manufacturing process is rolling the steel strip, to make the rolling direction have an angle with the direction of the pipe center, forming and welding, so the welding seam is in a spiral line.
Roller Pipes Process Flow
Range of roller pipes: Outer diameter: Ф1200-3800mm | Wall thickness: 12-120mm | Unit length (max) 3.2m.
The purpose of cold expansion for lsaw steel pipe
After cold expansion for lsaw steel pipe, steel tube and pipe end diameter will increase by about one percent difference in diameter of the diameter, roundness, and the pipe ends are greatly improved, also have greatly improved the straightness of the steel pipe, steel pipe length of about 0.5% reduction in wall thickness decreases by about 0.8%.
Fully develop LSAW process should consider these changes, to determine the pipe plate width, length and thickness, and the pipe diameter in front of the enlarged diameter, in order to avoid the enlarged diameter steel pipe geometry reach the final requirements caused by substandard.
The purpose of cold expansion for lsaw steel pipe has the followings:
(1) Improve pipe end geometric dimensional accuracy of LSAW steel pipe, so that the diameter of the steel tube and pipe end, roundness, and the diameter of the pipe ends Poor meet the standard requirements, facilitate field welding construction.
(2) Reduce inhomogeneous deformation of LSAW steel pipe forming and welding process and decrease the residual stress of forming and welding of tube, and improve its distribution, improve the overall mechanical properties of the steel pipe.
(3) Inspect the steel pipe overall performance comprehensively and effectively.
(4) Improve the straight degree of lsaw steel pipe, especially for the smaller diameter LSAW pipe straight is more obvious.
Longitudinally Submerged Arc Welded Steel pipes list:
Range of LSAW pipes applied in construction: Outer diameter: Ф350-1600mm, Wall thickness: 6-60mm, Unit length: 6-12m.
The coherence of cutter head and plate clamping system guarantees the invariable parameters during the entire milling process; accordingly it ensures the milling quality and lays a good foundation for the success of subsequent welding.
A superior technology center has been establish ed including the domestic first-class chenical laboratory,mechanics laboratory,the metallographic test laboratory and welding laboratory with advanced equipments for inspection and test Accordingly,
The developing trend of LSAW steel pipe
The developing trend of LSAW steel pipe in the future:
- in terms of the onshore gas,with the large diameter LSAW steel pipe, its single-tube gas transmission capacity could reach the level of 50 billion cubic meters / year, pipe diameter can reach ф1422mm, steel grade achieve X80, and gas transmission pressure can reach 12MPa;
- in terms of the ocean steel pipe, the gas pipeline develops towards the direction of deep-sea pipeline (> 1500 meters), marine structural tube towards the direction of high-intensity, large wall thickness, for example ф610mm×31.8mm, X65 grade;
- in terms of business management, plate and pipe integration (steelmaking – Continuous Casting – rolled plate – pipe manufacturing) is the future development trend, for example in Japan and India plate and strip production line is always equipped with a welded steel pipe unit;
- entering the market of high-grade structural tubes, this is an important question to be considered by the LSAW steel pipe production line manufacturer when deploying the device, so it is necessary to set the preheating device before pre-welding, or set the heat treatment process and so on;
- in marketing, in addition to oil and gas pipelines, there is slurry pipelines;
- anti HIC tube and anti deformed tube are with a considerable market prospect, can be used to transport acid gases and improve the ability against external environmental damage in harsh geological conditions (landslides, mudslides, earthquakes).
Advantages of LSAW steel pipe
In the long-distance pipeline construction, pipe-line account for a large proportion, generally 35% to 40% of line pipe accounts for investment projects total investment.
How to choose a reasonable price, excellent performance pipe is particularly important to a reasonable choice of pipe to save construction investment, easy construction and safe operation of the pipeline system has a very important influence. Gas Pipelines straight seam steel high-frequency electric resistance welded steel pipe, spiral submerged arc welded pipe, LSAW steel pipe.
Limited frequency straight seam electric resistance welded steel pipe diameter range is generally limited to domestic steel Φ406.4 mm or less, the largest in Japan has reached a diameter Φ508mm. For large diameter pipe in the form of a spiral SAW, LSAW two kinds. Spiral welded steel pipe because the pipe forming process and characteristics of many shortcomings, the proportion is gradually declining in the long-distance pipeline.
In other countries, especially in many European countries, it has banned the use of spiral submerged arc welded pipe used as the main line pipe. The advantage of its unique LSAW are widely used in long-distance oil and gas pipelines, and its advantages are as follows:
(1) without the unwind process, the base material indentation, scratch less.
(2) the wrong side, slotted, and other easy-to-diameter perimeter control, excellent welding quality.
(3) the elimination of flaring basically does not exist residual stress after stress.
(4) because it is a straight line weld, the weld is short, little risk of defects.
(5) after expanding, pipe geometry accuracy is improved greatly facilitate the on-site welding.
(6) for a straight seam, less impact on the quality of anti-corrosion coating materials.
Applications of SSAW pipe
For oil and gas pipeline systems, but in petroleum design specification, the SSAW pipe / HSAW pipe could only be applied in class 3 and class 4 areas. Construction structure, water transport and sewage treatment, thermal industry, buildings etc.
Here are comparisons of technological features and performance of these pipes:
High frequency straight seam welding (ERW) method is divided into two forms of induction welding and contact welding, hot-rolled wide volume as raw material, pre-curved, continuous molding, welding, heat treatment, sizing, straightening, cutting, etc. process, compared with the spiral weld short, high dimensional accuracy, uniform thickness, surface quality, pressure advantages, but the drawback is that only the production of small and medium-caliber thin-walled tube, weld easy to produce gray leaf spot, not fusion ditch-like corrosion defects. Wider application areas of city gas, crude oil transportation.
SSAW pipe is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral.
Spiral submerged arc pipe (SSAW pipe) is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral, the advantage of the same specification to produce a variety of diameter sizes steel pipe, raw materials to adapt to a wider range, the weld can avoid the main stress force better, the disadvantage is the poor geometry of the weld length compared to the long straight seam pipe, prone to cracking, porosity, slag, welding partial welding defects such as welding stress was tensile stress state. General Oil and Gas Pipeline design specification spiral submerged arc can only be used for Class 3, Class 4 regional. Raw materials instead will this process improvement abroad steel plate forming and welding separate pre-weld and lean and, after welding cold flaring near UOE pipe welding quality, currently no such process of plant improvement direction. “West-East” still is a traditional craft production, just expanded diameter of the pipe end. United States, Japan and Germany, the overall negative SSAW, think the mainline unfit for use SSAW; Canada and Italy part SSAW Russian small amount of SSAW, and have developed a very strict supplementary conditions, due to historical reasons, the majority of the domestic main trunk or use SSAW.
LSAW (LSAW) in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume) into using double-sided submerged arc welding and flaring from production. A wide range of the finished product specifications, weld toughness, ductility, uniformity and dense, with a large diameter, wall thickness, high pressure resistance, low-temperature corrosion resistance, etc.. Required steel pipe in the construction of high-strength, high toughness, high-quality long-distance oil and gas pipelines, mostly large diameter thick wall LSAW.
API standard provisions, in the large-scale oil and gas pipelines, when 1, Class 2 areas through the alpine zone, the bottom of the sea, the city densely populated area, LSAW only applied specifically casts. Molding can be divided into:
UOE: leaflets steel plate after the edge preflex, after U molding, O forming within welding, the outer welding, mechanical cold expanded diameter process;
JCOE: Press “JCOE” pre-welding, forming, welding after cold expanded diameter process.
Source: China Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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